219 lines
8.7 KiB
JavaScript
219 lines
8.7 KiB
JavaScript
"use strict";
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import RouterContext from './RouterContext.mjs';
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import pathspec_to_regex from '../Shared/Pathspec.mjs';
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/**
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* A standalone HTTP router that's based on the principle of middleware.
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* Based on rill (see the npm package bearing the name), but stripped down and
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* simplified.
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* @param {Boolean} verbose Whether to be verbose and log a bunch of things to the console. Useful for debugging.
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*/
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class ServerRouter
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{
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constructor(verbose = false) {
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/**
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* The actions to run in turn.
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* @private
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* @type {Array<Function>}
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*/
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this.actions = [];
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/** Whether to activate verbose mode. Useful for debugging the router. */
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this.verbose = verbose;
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this.default_action = async (ctx) => {
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let message = `No route was found for '${ctx.request.url}'.`;
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if(this.verbose) {
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message += `\n\nRegistered Actions:\n`;
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for(let action of this.actions) {
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message += ` - ${action.toString()}\n`;
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}
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}
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ctx.send.plain(404, message);
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}
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}
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/**
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* Shortcut function for attaching an action to any request method.
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* Full function: on
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* @param {string|RegExp} pathspec The pathspec that the route should match against.
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* @param {Function} action The function to execute when this route is matches.gets passed 2 parameters: context (or type RequestContext) and next (a function). context contains the request / response objects, and next() should be called if the action is middleware.
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*/
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any(pathspec, action) { this.on("*", pathspec, action); }
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/**
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* Shortcut function for attaching an action to head requests. Full function: on
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* @param {string|RegExp} pathspec The pathspec that the route should match against.
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* @param {Fuction} action The function to execute.
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* @example
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* router.head("/location/:name/status", (context, _next) => {
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* context.send.plain(200, `Coming in from ${context.params.type} - status ok!`);
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* });
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*/
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head(pathspec, action) { this.on(["head"], pathspec, action); }
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/**
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* Shortcut function for attaching an action to get requests. Full function: on
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* @param {string|RegExp} pathspec The pathspec that the route should match against.
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* @param {Fuction} action The function to execute.
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* @example
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* router.get("/tree/:type", (context, _next) => {
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* context.send.plain(200, `Hello, I am a ${context.params.type}`);
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* });
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*/
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get(pathspec, action) { this.on(["get"], pathspec, action); }
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/**
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* Shortcut function for attaching an action to post requests. Full function: on
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* @param {string|RegExp} pathspec The pathspec that the route should match against.
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* @param {Fuction} action The function to execute.
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* @example
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* router.post("/loaction/:name/update", (context, _next) => {
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* context.send.plain(501, `Hello from ${context.params.name}! I don't yet support updating my firmware.\nYou asked me to update to version ${context.post_data.version}.`);
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* // See https://github.com/sbrl/powahroot/blob/master/examples/parse_post_data.mjs for an example of parsing post data with middleware that works with the above (context.post_data is not created automatically by powahroot)
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* });
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*/
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post(pathspec, action) { this.on(["post"], pathspec, action); }
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/**
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* Shortcut function for attaching an action to put requests. Full function: on
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* @param {string|RegExp} pathspec The pathspec that the route should match against.
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* @param {Fuction} action The function to execute.
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*/
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put(pathspec, action) { this.on(["put"], pathspec, action); }
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/**
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* Shortcut function for attaching an action to delete requests. Full function: on
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* @param {string|RegExp} pathspec The pathspec that the route should match against.
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* @param {Fuction} action The function to execute.
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*/
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delete(pathspec, action) { this.on(["delete"], pathspec, action); }
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/**
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* Shortcut function for attaching an action to options requests. Full function: on
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* @param {string|RegExp} pathspec The pathspec that the route should match against.
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* @param {Fuction} action The function to execute.
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* @example
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* router.options("/location/:name/status", (context, _next) => {
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* context.send.plain(200, `I support these actions:\n - GET: Get my status\n - POST: Set my status\n - OPTIONS: Show this message`);;
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* });
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*/
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options(pathspec, action) { this.on(["options"], pathspec, action); }
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/**
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* Execute the specified action for requests matching the given parameters.
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* TODO: Consider merging with on_all and refactoring to take an object literal which we can destructure instead
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* @param {array} methods The HTTP methods to run the action for. Include '*' to specify all methods.
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* @param {string|regex} pathspec The specification of the paths that this action should match against. May be a regular expression.
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* @param {Function} action The action to execute. Will be passed the parameters `context` (RouterContext) and `next` (Function).
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* @example
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* router.on(["get"], "/garden/:vegetable", (context) => {
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* context.send(201, `Planted ${context.params.vegetable}`);
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* });
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*/
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on(methods, pathspec, action) {
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let regex_info = pathspec instanceof RegExp ? {regex: pathspec, tokens: [] } : pathspec_to_regex(pathspec);
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// next must be a generator that returns each action in turn
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this.actions.push(async (context, next) => {
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const matches = context.url.pathname.match(regex_info.regex);
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if(this.verbose) console.error(`[router/verbose] [${methods.join(", ")} -> ${pathspec} ] Matches: `, matches);
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if((methods.indexOf(context.request.method.toLowerCase()) > -1 || methods.indexOf("*") > -1) && matches) {
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if(this.verbose) console.error(`[router/verbose] Match found! Executing action.`);
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for(let i = 1; i < matches.length; i++) { // Skip the top-level group
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context.params[regex_info.tokens[i-1]] = matches[i];
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}
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await action(context, next);
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}
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else {
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if(this.verbose) console.error(`[router/verbose] Nope, didn't match. Moving on`);
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await next();
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}
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});
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}
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/**
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* Adds a route that matches against every request.
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* Usually useful for middleware (e.g. error handlers, request loggers, authentication handlers, etc.).
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* @param {Function} action The function to execute.
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* @example
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* router.on_all((context) => {
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* context.send.plain(200, "Hello, world!");
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* });
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*/
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on_all(action) {
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this.actions.push(action);
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}
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/**
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* Runs the specified action for requests if the provided testing function
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* returns true.
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* @param {Function} test The testing function. Will be passed the context as it's only parameter.
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* @param {Function} action The action to run if the test returns true.
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*/
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onif(test, action) {
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this.actions.push(async (context, next) => {
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let test_result = test(context);
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if(this.verbose) console.error("[router/verbose] Test action result: ", test_result);
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if(test_result)
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await action(context, next);
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else
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await next(context);
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})
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}
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/**
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* Handles the specified request.
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* Don't forget to await the Promise!
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* @param {http.ClientRequest} request The request to handle.
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* @param {http.ServerResponse} response The response object to use to send the response.
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* @return {Promise} A Promise that resolves when handling is complete.
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* @example
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* const server = http.createServer(async (request, response) => {
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* await router.handle(request, response);
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* });
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* server.listen(3500, "127.0.0.1", () => console.log("Listening on http://127.0.0.1:3500/"));
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*/
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async handle(request, response) {
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let context = new RouterContext(request, response),
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iterator = this.iterate();
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// Begin the middleware execution
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this.gen_next(iterator, context)();
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}
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/**
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* Returns an anonymous function that, when called, will execute the next
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* item of middleware.
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* It achieves this via a combination of a generator, anonymous function
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* scope abuse, being recursive, and magic.
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* You shouldn't need to call this directly.
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* @private
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* @param {Generator} iterator The generator that emits the middleware.
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* @param {Object} context The context of the request.
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* @return {Function} A magic next function.
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*/
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gen_next(iterator, context) {
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let next_raw = iterator.next();
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// Return the default action if we've reached the end of the line
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if(next_raw.done)
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return async () => {
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this.default_action(context);
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};
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return (async () => {
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if(this.verbose) console.error(`[router/verbose] Executing ${next_raw.value}`);
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await next_raw.value(context, this.gen_next(iterator, context));
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}).bind(this); // Don't forget to bind each successive function to this context
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}
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/**
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* Iterates over all the generated middleware.
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* @return {Generator} A generator that returns each successive piece of middleware in turn.
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* @generator
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*/
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*iterate() {
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for(let action of this.actions) {
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yield action;
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}
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}
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}
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export default ServerRouter;
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